The Internet has become an increasingly popular medium for delivering full motion video to end users. Due to bandwidth constraints, however, most users are unable to download and view high quality video on demand. For example, to deliver a compressed 640 by 480 pixel resolution video at thirty frames per second, image data must be transmitted at approximately eight Mbs (mega-bits per second), a bandwidth requirement roughly three hundred times more than the 28.8 Kbs (kilo-bits per second) modem speed available to most Internet users today. Even using industry standard compression techniques (e.g., MPEG--Moving Picture Expert Group), video effects on the Internet today are usually more like a low-quality slide show than a television experience.
Animations, which use keyframes and interpolation to create video effects, potentially require much less bandwidth to transmit than video. With the improved performance of personal computers, television quality video effects can be synthesized in real-time from a relatively few keyframes that can be received using a low bandwidth modem. An animation sequence that requires transmission of a keyframe every few seconds can be delivered with an enormous bandwidth savings relative to video and yet provide exceptional image quality.
In addition to having a small bandwidth requirement, animations are also more scalable than videos in both playback image quality and frame rate. Because the video effects are synthesized on the fly during playback time, the frame rate and image quality can be dynamically adjusted based on a number of factors, such as playback processor speed, network bandwidth and user preferences.
Adding features for user interaction and other types of editing is also significantly easier with an animation than with a video. For instance, adjusting a camera panning path or object movement speed may only require changing motion parameters associated with a few keyframes in the animation. Editing a video clip to achieve the same effects may require modification of hundreds of frames. Similarly, attaching a hot spot that tracks a moving object over time can be achieved far easier in an animation than in a video.
Animation has its drawbacks. Because skilled human animators have traditionally been required to create high quality animation, the animation process is often costly and expensive. Further, because the human animators often sketch keyframes by hand, animation tends to appear cartoonish and usually lacks the lifelike imagery needed to depict real world scenes. In some cases animations are created using primitive two-dimensional and three-dimensional objects as building blocks. This type of animation also tends to have a synthetic rather than a natural appearance and is usually limited to presenting graphic information.